The present invention relates to fluid treatment apparatus and to a casing for enclosing and compressing a stack of elements in such an apparatus. It also relates to a process for forming the fluid treatment apparatus.
The stack may be such that it forms part of a blood treatment apparatus, such as a blood dialyser, blood filter or blood oxygenator, but the stack can also be intended for use in heat exchangers, gas filters, or separation devices or exchange devices in general. Such stacks usually consist of substantially plane elements, hereafter referred to as "elements". The elements can for example be sheets of semi-permeable membranes, or relatively thin plates, but can also be sheets of semi-permeable membranes together with their support plates.
The object of the present invention is to provide a casing which forms an envelope and which makes it possible to subject a stack such as described above to a compressive force, which essentially serves the purpose of establishing uniform and thin flow passages for the fluid or fluids which circulate in contact with the elements.